Table 1.
NMDA receptor subunits (NR1,NR2 and NR3) of mRNA distribution and their functions. (Adapted from Benarroch, 2011).
| Subunit type | NR1 (GluN1) | NR2 (GluN2) | NR3 (GluN3) |
|---|---|---|---|
| Predominant distribution | Throughput the CNS | Hippocampus (NR2A, NR2B) | Neurons |
| Neocortex (NR2A, NR2B) | Oligondedrocytes | ||
| Cerebellum in purkinje cell (NR2A, NR2C), molecular (NR2B) and granule cell (NR2C) layers | |||
| Cortical interneuron (NR2C) | |||
| Brainstem (NR2C) | |||
| Variants | Eight splice variants | ||
| Function in NMDAR | Obligatory | NR2A or NR2B are most common in NR1/NR1 receptors | Activated by binding or glycine only |
| Binding glycine | Binding glutamate | ||
| Binding site | Glycine | Glutamate | Glycine |
| Modulatory sites | Polyamines | Zn2+ | – |
| Protons | Redox site | ||
| Nitric oxide site (nitrosylation) | |||
| Predominant location | Postsynaptic density (PSD) and extra synaptic | NR2A; PSD | Dendritic spines during development |
| NR2B: Extrasynaptic (NR2A/NR2B ratio increases in adult brain) | Oligodendrocytes |